Chapter 4 Computer Software Slide 1 Well, Sort-of.

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4 Computer SoftwareComputer SoftwareComputer SoftwareComputer Software

Slide 1

Well, Sort-of

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Various kinds of programs used to operate computers and related devices

What is Software??What is Software??

How did it come about??How did it come about??

The first software program was actually written about 1833 by Ada Augusta Lovelace (Lord Byron’s Daughter)

We can skip forward to computer programs, however

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Programming Languages First Generation Languages (Machine Language)

Suppose that I wanted to add two numbers together, for example 2 + 3 • First, we would have to move the values into

two registers in the CPU’s Internal StorageR1 R2

2 3

• Next I would have the ALU to add the contents of the registers and store the result in Register 2 (maybe)

R2

5

(Well, Kind of – It’s a little more involved)

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We Actually have to do a few things. • First we have to find the operating code, or op code (by

number) to move the data (let’s assume the command is number 28)

• Of course, we have know the identifying number for each of the registers (assume R1 = 12; R2 = 13)

• Finally, we have to find the op code for addition (Assume it is 37).

• The code I enter might be:

28 2 12;28 3 13;37 12 13 13;

(Well, Kind of – It’s a little more involved)

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Let’s not forget that the computer is just a series of light-switches (binary). Therefore we need to convert our decimal values to binary:

2 = 000000000000010 (on 16-bits)3 = 000000000000011 (on 16-bits)12 = 00001100 (on 8-bits)13 = 00001101 (on 8-bits)28 = 00011100 (on 8-bits)37 = 00100101 (on 8-bits)

Therefore, We would enter the commands:

00011100 000000000000010 00001100;00011100 000000000000011 00001101;00100101 00001100 00001101 00001101;

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Programming Languages Second Generation Languages (Assembly – c1948)

The advancement over machine level languages was that it was mnemonic (assisting or intended to assist the memory)• We did not need to know the specific register

addresses• We did not need to know the op codes• For the previous example, the code we enter might be:

MOV 2 R1;MOV 3 R2;ADD R1 R2 R2;

An Assembler would then transfer the commands into a machine level language

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Programming Languages Third Generation Languages (mid - late 1950’s)

The advancement over assembly level languages was that programmers did not need to know either the op codes nor the registers used • Specific locations in RAM were referred to by a user

defined name• The compiler or interpreter, as well as the operating

system, kept track of the specific locations

• For the previous example, the code we enter might be:

X = 2 + 3 (FORTRAN)

The code would then be rewritten as either an assembly language code or directly to a machine level language

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Programming Languages Third Generation Languages (mid – late1950’s)

In the above example ‘X’ is a specific location in RAM, although we don’t have to know where it is

• It is usually referred to as a variable

• Although it can be a constant

• Meaning that we can change the contents of the location as we wish

• Meaning that once we set its value, it can not be changed

Either way, the address is assigned by the operating system at run time and managed by the compiled program (i.e., the machine-level program)

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Programming Languages Comparison of COBOL and FORTRAN (Hello World)

COBOL (COmmon Business-Oriented Language)

• 001 IDENTIFICATION DIVISION.• 002 PROGRAM-ID. 'HELLO'.• 003 ENVIRONMENT DIVISION.• 004 CONFIGURATION SECTION.• 005 SOURCE-COMPUTER. IBM-360.• 006 OBJECT-COMPUTER. IBM-360.• 0065 SPECIAL-NAMES.• 0066 CONSOLE IS CNSL.• 007 DATA DIVISION.• 008 WORKING-STORAGE SECTION.• 009 77 HELLO-CONST PIC X(12) VALUE 'HELLO, WORLD'.• 075 PROCEDURE DIVISION.• 090 000-DISPLAY.• 100 DISPLAY HELLO-CONST UPON CNSL.• 110 STOP RUN.

• Intended to process large amounts of data as a batch

• Edsger Dijkstra, winner of the Turing Award remarked that "The use of COBOL cripples the mind; its teaching should, therefore, be regarded as a criminal offense."

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Programming Languages Comparison of COBOL and FORTRAN (Hello World)

FORTRAN (FORmula TRANslation)

PROGRAM MAIN PRINT *, 'HELLO WORLD' STOP END

• Intended as a ‘Scientific Language’

• It is one of the most popular languages in the area of high-performance computing and is the language used for programs that benchmark and rank the world's fastest supercomputers.

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Programming Languages Third Generation Languages (mid 1950’s)

Third generation languages are Procedural in nature

• If, for example, we want to find the average age of a class, we need to know the procedures involved• We need to add every persons age in a class

together

• We then need to divide the sum of every persons age by the number of people in the class

• The result is the average age of the class

Third generation languages are also known as structured programming

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Third generation languages are also referred to as ‘High-level Languages’ (so are 4th generation languages)

Third generation languages (as well as 4th generation languages) may be either interpreted or translated languages (although they are generally translated)

What’s the difference??What’s the difference??

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Think of a person who works at the United Nations

As soon as these people get a phrase of what a person is talking about, they put it into the language which they are interpreting

At the end of the day, they might not even know what the speech was about

(That is not their job)

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Now think of someone whose job is to translate a book from one language to another

• S/he will read the book many times

• S/he will try and find the best way to say what the author was trying to say

(That IS their job)

What does this have to do with computers??What does this have to do with computers??

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There are two classes of program languages

• Those that are interpreted

• Those that are translated or compiled

• BASIC started as an interpreted language

• The compiler makes a few ‘passes’ through the code• It first checks syntax• It next checks simple logic• It sets-up variable tables

• The compiler creates a separate executable (.exe) or command file (.com)

• These file are machine language files

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Third generation languages are also referred to as ‘High-level Languages’ (so are 4th generation languages)

• If, for example, we want to find the average age of a class, we need to know the procedures involved• We need to add every persons age in a class

together

• We then need to divide the sum of every persons age by the number of people in the class

• The result is the average age of the class

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Programming Languages Fourth Generation Languages (4GLs)

4GLs are non-procedural languages

• If, for example, we want to find the average age of a class, we need to enter the command

• The procedures are built-into the commands

Get Class Average(or something similar)

• These end result is still the creation of machine language files

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Programming Languages Fifth Generation Languages (5GLs)

Maybe --- Someday

• Sounds a little like a Star Trek episode

“Computer – Save the world”

The intention is have speech recognition Artificial Intelligence (AI) programs that allow speech recognition

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Programming Languages Programming Tools

Help programmers identify and minimize errors while they program

• Graphical Programming environments: Akin to toolbars and menus

Provide a computer-aided programming environment

• Program Editors: Packages for source code creation which check key words, structures as the program is typed in

• Debuggers: a computer program that is used to test and debug other programs.

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Programming Languages Computer-Aided Software Engineering (CASE)

Allow program development through the use of system development models

• e.g., Entity Relationship Diagrams

Once the model has been constructed, the CASE tool constructs the data dictionary and can create the DBMS code (in SQL or any other language)

• An ERD is a model for graphically showing the contents of a database table and its relationships to other tables

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Programming Languages Web Languages

Languages for building multi-media web applications

• Page description language that creates hypertext and hypertext linkages

Hypertext Mark-up Languages (HTML)

• Hyperlinks: allows control to be given to other parts of a document or to any document on the WWW

• HTML can be created from various programs (Word, Frontpage) without formal training in HTML

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• Describes the contents of webpages by applying identifying tags (contextual labels) to the data in web documents

eXtesible Markup Languages (XML)

• Its primary purpose is to facilitate the sharing of data across different information systems, particularly systems connected via the Internet

• XML supports the automatic electronic exchange of business data between companies and their customers, vendors, suppliers and partners

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• OOP language

Java

• Consists of small applets that can be connected and used on any operating system

• Programmers are spared the burden of having to perform manual memory management.

• Your On-line quizzes are Javascripts

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• OOP language an object-oriented programming language that is simple, secure and platform independent

Java

• Consists of small applets that can be connected and used on any operating system

• Programmers are spared the burden of having to perform manual memory management.

• Your On-line quizzes are Javascripts

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Programming Languages Object Oriented Programming (OOP)

Sometimes also referred to as 5GLs (???)

• C++

An object consists of data and procedures that can be performed on the data

• Java• Visual Basic

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End Users

Applications Software

General Purpose – Application Specific

System Software

System Mgt & Development

Types of Software

Computer Hardware

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Types of Software

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Types of Software

Systems Management Programs

Computer Software

System Software

System Management

Programs

System Development

Programs

These have already been covered

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System Software

Programs that manage the hardware, software, network, and data resources of computer systems

Operating Systems

• An integrated system of programs that manages the operations of the CPU, controls I/O, storage resources and provides various support services as the computer executes applications

UNIX

Windows/Vista

Linux

Mac OS X

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Operating System Interfaces

The part of the OS that allows communication with it to load programs, access files, and accomplish other tasks

Types:• Command-Driven• Menu-Driven

• GUI

System Software

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Operating System Functions

• Programs to manage the hardware and networking resources of a computer system, including its CPU, memory, secondary storage devices, telecommunications processors, and input/output peripherals

Resource Management

Memory management programs keep track of where data and programs are stored

Swapping of programs of programs between RAM and secondary storage

Swapping allows for virtual memory whereby programs can process more than RAM would normally allow

System Software

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• Programs to control the creation, deletion and access of data and programs

File Management

Keeping track of the physical location of files on secondary storage

Maintaining directories of information about the location and characteristics of files stored on secondary storage


System Software

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• Managing the accomplishment of several programs

Task Management

Your text applies that multitasking and multi-programming are the same (NOT):

Multitasking: performing many applications at what appears to be the same time (not possible if you have you have only 1 CPU)

Multiprocessing: performing many applications at the same time (assumes that you have more than 1 CPU – but be careful: 2 processors does not imply you can do twice the work of 1)


System Software

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Utilities: Consider those available in XP: Operating System Functions

System Software

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Security Monitors: Monitor and control computer usage, checking for unauthorized usage

Character Map: Preferred Character set

Disk Clean-up: Archiving/deleting infrequently used programs/data

Disk defragmenter: Putting fragmented files back together so they con be collected faster

Performance Monitors: Monitor and adjust the performance of computer systems to keep them running efficiently


System Software

Utilities: Consider those available in XP:

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Other Systems Software

Middleware: software that helps diverse software applications and networked computer systems exchange data and work together more efficiently• Web Servers• Enterprise Application Integration (EAI)

• Application Servers: Software which provides an interface between an operating system and application programs of users


System Software

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Operating Systems

• The founding goal of the GNU project was, in the words of its initial announcement, to develop "a sufficient body of free software [...] to get along without any software that is not free."

Linux created by Linus Torvalds in 1991 includes system utilities & libraries

from the GNU Project

Open Source Hardware: • Free• Stable• Easily fixed if bugs appear

(A quick Aside)

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Operating Systems

Linux

Low-cost alternative in sagging economy

IBM made an effort to be Linux-compatible

Why did Linux become popular??Why did Linux become popular??

Fear of Microsoft gaining a stranglehold on corporate customers

Intel loosened its relationship with Microsoft

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Operating Systems

Linux

Linux runs almost 15% of all servers

Only 1% of PCs use Linux but 30% of CIOs were considering moving their companies’ PCs to Linux

How is Linux doing??

Growing at 23% per year

Over 10% of IBM mainframe sales run Linux

By 2011, Linux was running 95% of all Supercomputers.

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Types of Software

Applications Software: perform information processing tasks for end users

Computer Software

Application Software

General Purpose

Applications

Application Specific

Programs

programs that perform common information processing jobs for end users

support specific applications of end users in business and other fields

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General-Purpose Application Software

Software Suites: Several programs bundled together

• Cheaper than cost of all individual programs• Use similar GUIs (Icons, menus, etc)• Share similar tools (spell checkers, wizards, hot keys)• Problem: Bloatware

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Integrated Packages: Provides some of the features of several programs in one software package• Omit some features found in software suites• Cheaper• Requires less storage

Web Browsers: Software interface used to point and click through the hyperlinked resources of the Internet

• MS Explorer• Netscape navigator (defunct)• Mozilla Foxfire (freeware)

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General-Purpose Application Software Electronic Mail: software used to send

and receive electronic messages and file attachments via the Internet, intranets or extranets• MS Outlook, Yahoo!Mail, Gmail

Instant Messaging: software used to send and receive electronic messages instantly to facilitate real time communication and collaboration

• AOL Instant Messenger• MSN Messenger• Yahoo! Messenger

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Word Processing: software that supports the creation, editing, revision and printing of documents• Include features such as spellchecking,

thesaurus, and grammar correction

Desktop Publication: software that supports the production of materials that look professionally published

• Professional quality publications which integrate text and graphics

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Electronic Spreadsheets: Software that supports the development of electronic worksheets consisting of rows and columns used for business analysis, planning and modeling

Presentation Graphics: Software that helps convert numeric data into graphics displays and prepare multimedia presentations including graphics, photos, animation, and video clips

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Video Software: Software that supports the development of full video, usually along with text and audio

Personal Information Manager (PIM): Software for end user productivity and collaboration

• It usually includes the ability to import and export video, cut and paste sections of a video clip, add special effects and transitions

• Organizes data and retrieves information in a variety of forms (e.g., calendar) and allows distribution to others

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Groupware: Software that helps workgroups and teams work together to accomplish group assignments• Also called collaborative software• Relies on the Internet, Intranets and

Extranets on a global scale by virtual teams located anywhere in the world

• Lotus Notes• Microsoft Exchange• Microsoft’s SharePoint and IBM’s Webshare allow quick

creation of websites to share information

• MS Word and MS Excel keep track of who made changes to the documents

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Software Implementation

Custom Software: software applications that are developed within an organization for use by that organization

Commercial Off-the-shelf (COTS) Software: software that is developed by a software developer with the intention of selling the software in multiple copies

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Software Implementation The Buy (COTS) v. Build (Custom) Argument

COTS• Cheaper acquisition and deployment costs• Thoroughly Tested• Documentation included• Over time, the number of applications have increased dramatically

• COTS software packages, even customized, are probably less suited to your firm’s specific needs and challenges

• You can readily make changes as necessary• You can specify which modules to include• You control the quality of documentation

Build

Bottom Line

• BUY if the system if a fundamental requirement of doing business• BUILD if the system gives you a competitive advantage

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Application Service Providers (ASP): companies that own, operate, and maintain application software and the computer system resources required to offer the use of the application software for a fee as a service over the Internet• Lower cost of initial investment• Lower cost of operating and maintaining software• Reduces the need for much of the IT Infrastructure

and IT Personnel


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Software Licensing: Purchasing the right to use specific software under the terms of the software licensing agreement

• Intended to protects the vendor’s intellectual property right

• Purchasing a piece of software does NOT mean ownership; it is a license to use the software

• The license prohibits duplication or resale of multiple copies of the software


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Chapter 4 Computer Software Slide 1 Well, Sort-of.

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